Wireless device discovery in a wireless peer-to-peer network

ABSTRACT

Systems and methodologies are described that facilitate detecting and/or identifying peers in a local area peer-to-peer network. Times (e.g., peer discovery intervals) for performance of mutual detection and identification between peers may be synchronized (e.g., based upon a signal broadcast to the peers). Further, within each partitioned peer discovery interval, a wireless terminal may select a portion of time to transmit (e.g., broadcast) short messages that may be employed by peers to detect and/identify the wireless terminal. Moreover, the remainder of the time within the partitioned peer discovery interval may be employed to listen to short messages received from peers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent application Ser. No, 60/758,010 entitled “METHODS AND APPARATUS FOR FACILITATING IDENTIFICATION, SYNCHRONIZATION OR ACQUISITION USING BEACON SIGNALS” which was filed Jan. 11, 2006; U.S. Provisional Patent application Ser. No. 60/758,011 entitled “METHODS AND APPARATUS FOR USING BEACON SIGNALS FOR IDENTIFICATION, SYNCHRONIZATION OR ACQUISITION IN AN AD HOC WIRELESS NETWORK” which was filed Jan. 11, 2006; U.S. Provisional Patent application Ser. No. 60/758,012 entitled “METHODS AND APPARATUS FOR USING BEACON SIGNALS IN A COGNITIVE RADIO NETWORK” which was filed Jan. 11, 2006; U.S. Provisional Patent application Ser. No. 60/845,052 entitled “POWER ALLOCATION SCHEME” which was filed Sep. 15, 2006; U.S. Provisional Patent application Ser. No. 60/845,051 entitled “BEACONS IN A MIXED WIRELESS COMMUNICATION SYSTEM” which was filed Sep. 15, 2006; and U.S. Provisional Patent application Ser. No. 60/863,304 entitled “BEACONS IN A MIXED COMMUNICATION SYSTEM” which was filed Oct. 27, 2006. The entireties of the aforementioned applications are herein incorporated by reference.

BACKGROUND

I. Field

The following description relates generally to wireless communications, and more particularly to enabling peers to discover and identify each other in a peer-to-peer network.

II. Background

Wireless communication systems are widely deployed to provide various types of communication; for instance, voice and/or data may be provided via such wireless communication systems. A typical wireless communication system, or network, can provide multiple users access to one or more shared resources. For instance, a system may use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Orthogonal Frequency Division Multiplexing (OFDM), and others.

Common wireless communication systems employ one or more base stations that provide a coverage area. A typical base station can transmit multiple data streams for broadcast, multicast and/or unicast services, wherein a data stream may be a stream of data that can be of independent reception interest to a wireless terminal. A wireless terminal within the coverage area of such base station can be employed to receive one, more than one, or all me data streams earned by the composite stream. Likewise, a wireless terminal can transmit data to the base station or another wireless terminal.

Wireless communication systems leverage various portions of wireless spectrum for transferring data. However, wireless spectrum is an expensive and valuable resource. For example, significant coats may be incurred by a company desiring to operate a wireless communication system over a portion of the wireless spectrum (e.g., within the licensed spectrum). Further, conventional techniques typically provide inefficient utilization of wireless spectrum. According to a common illustration, the spectrum allocated for wide area network cellular communication oftentimes is not uniformly utilized across time and space; thus, a significant subset of spectrum may be unused in a given geographic location or in a given time interval.

According to another example, wireless communication systems oftentimes employ peer-to-peer or ad hoc architectures whereby a wireless terminal may transfer signals directly to another wireless terminal. As such, signals need not traverse through a base station; rather, wireless terminals within range of each other may discover and/or communicate directly. However, conventional peer-to-peer networks typically operate in an asynchronous manner whereby peers may effectuate differing tasks at a particular time. Consequently, peers may encounter difficulty associated with identifying and/or communicating with disparate peers within range, power may be inefficiently utilized, and so forth.

SUMMARY

The following presents a simplified summary of one or more embodiments in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated embodiments, and is intended to neither identify key or critical elements of all embodiments nor delineate the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

In accordance with one or more embodiments and corresponding disclosure thereof, various aspects are described in connection with facilitating detection and/or identification of peers in a local area peer-to-peer network. Times (e.g., peer discovery intervals) for performance of mutual detection and identification between peers may be synchronized (e.g., based upon a signal broadcast to the peers). Further, within each partitioned peer discovery interval, a wireless terminal may select a portion of time to transmit (e.g., broadcast) short messages that may be employed by peers to detect and/identify the wireless terminal. Moreover, the remainder of the time within the partitioned peer discovery interval may be employed to listen to short messages received from, peers.

According to related aspects, a method of operating a first wireless terminal in a peer-to-peer network is described herein. The method may include receiving a first signal from a signal source wherein the signal source is at least one of a base station, an access node, or a GPS satellite. Further, the method may comprise determining time positions of a first sequence of peer discovery intervals based upon the received first signal.

Another aspect relates to a wireless communications apparatus. The wireless communications apparatus may include a memory that retains instructions related to obtaining a first signal from a signal source and identifying time positions of a first sequence of peer discovery intervals based upon the obtained first signal. Further, the wireless communications apparatus may include a processor, coupled to the memory, configured to execute the instructions retained in the memory.

Yet another aspect relates to a wireless communications apparatus that enables synchronizing a time period for discovery of peers in a peer-to-peer network. The wireless communications apparatus may include means for receiving a first signal from a signal source; and means for locating time positions of a first sequence of peer discovery intervals based upon the first signal.

Still another aspect relates to a machine-readable medium having stored thereon machine-executable instructions for obtaining a first signal from a base station, and determining time positions of a sequence of peer discovery intervals as a function of the obtained first signal, the sequence being synchronized with disparate sequences of peers in a peer-to-peer network based upon the obtained signal.

In accordance with another aspect, an apparatus in a wireless communication system may include a processor, wherein the processor may be configured to obtain a periodic signal from a base station. Additionally, the processor may be configured to identify time positions of a sequence of peer discovery intervals based upon the obtained periodic signal, wherein the sequence of peer discovery intervals is synchronized between peers of a peer-to-peer network.

To the accomplishment of the foregoing and related ends, the one or more embodiments comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the one or more embodiments. These aspects are indicative, however, of but a few of the various ways in which the principles of various embodiments may be employed and the described embodiments are intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a wireless communication system in accordance with various aspects set forth herein.

FIG. 2 is an illustration of an example system that synchronizes communication between wireless terminals in a peer-to-peer network.

FIG. 3 is an illustration of an example timing diagram utilized by synchronized peers communicating within a peer-to-peer environment.

FIG. 4 is an illustration of an example timing diagram of a peer discovery interval.

FIG. 5 is an illustration of an example system that effectuates synchronized communications over a peer-to-peer network.

FIG. 6 is an illustration of an example time-frequency grid associated with transmission during a peer discovery interval.

FIG. 7 is an illustration of an example methodology that facilitates operating a wireless terminal in a peer-to-peer network.

FIG. 8 is an illustration of an example methodology that facilitates transmitting a message that enables peers to detect and identify a wireless device in a peer-to-peer network.

FIG. 9 is an illustration of an example methodology that, facilitates detecting and identifying peers in a peer-to-peer network.

FIG. 10 is ah illustration of an example communication system implemented in accordance with various aspects including multiple cells.

FIG. 11 is an illustration of an example base station in accordance with various aspects.

FIG. 12 is an illustration of an example wireless terminal (e.g., mobile device, end node, . . . ) implemented in accordance with various aspects described herein.

FIG. 13 is an illustration of an example, system that enables synchronizing a time period for discovery of peers in a peer-to-peer network.

DETAILED DESCRIPTION

Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments.

As used in this application, the terms “component,” “module,” “system,” and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the Internet with other systems by way of the signal).

Furthermore, various embodiments are described herein in connection with a wireless terminal. A wireless terminal can also be called a system, subscriber unit, subscriber station, mobile station, mobile, mobile device, remote station, remote terminal, access terminal, user terminal, terminal, wireless communication device, user agent, user device, or user equipment (UE). A wireless terminal may be a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device having wireless connection capability, computing device, or other processing device connected to a wireless modem. Moreover, various embodiments are described herein in connection with a base station. A base station may be utilized for communicating with wireless terminal(s) and may also be referred to as an access point, Node B, or some other terminology.

Moreover, various aspects or features described herein may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques. The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. For example, computer-readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, etc.), optical disks (e.g., compact disk (CD), digital versatile disk (DVD), etc.), smart cards, and flash memory devices (e.g., EPROM, card, stick, key drive, etc.). Additionally, various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term “machine-readable medium” can include, without being limited to, wireless channels and various other media capable of storing, containing, and/or carrying instruction(s) and/or data.

Referring now to FIG. 1, a wireless communication system 100 is illustrated in accordance with various embodiments presented herein. System 100 may comprise one or more wireless terminals 102. Although two wireless terminals 102 are depicted, it is to be appreciated that system 100 may include substantially any number of wireless terminals 102. Wireless terminals 102 can be, for example, cellular phones, smart phones, laptops, handheld communication devices, handheld computing devices, satellite radios, global positioning systems, PDAs, and/or any other suitable device for communicating over wireless communication system 100. Wireless terminals 102 can communicate directly with each other via a local area peer-to-peer (P2P) network (e.g., ad hoc network). Peer-to-peer communication may be effectuated by directly transferring signals between wireless terminals 102; thus, the signals need not traverse through a base station (e.g., base station 104). The peer-to-peer network may provide short range, high data rate communication (e.g., within a home, office, etc. type setting).

Further, system 100 may support, a wide area network (WAN). System 100 may include a base station 104 (e.g., access point) and/or any number of disparate base stations (not shown) in one or more sectors that receive, transmit, repeat, etc. wireless communication signals to each other and/or to one or more wireless terminals 102. Base station 104 can comprise a transmitter chain and a receiver chain, each of which can in turn comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, . . . ) as will be appreciated by one skilled in the art. Wireless terminal(s) 102 may transmit signals to and/or receive signals from base station 104 when communicating via the wide area infra-structure network supported by system 100.

Peer-to-peer communication between wireless terminals 102 may be synchronous. For example, wireless terminals 102 may utilize a common clock reference to synchronize performance of distinct functions. Wireless terminals 102 may obtain timing signals from base station 104 (and/or a transmitter (not shown) that provides less functionality) utilized to synchronize operation of wireless terminals 102. Wireless terminal 102 may obtain timing signals from other sources, such as GPS satellites. According to an illustration, time may be meaningfully partitioned in a peer-to-peer network for functions such as peer discovery, paging, and traffic. Further, it is contemplated that each peer-to-peer network may set its own time.

Before communication in a peer-to-peer network can take place, wireless terminals 102 (e.g., peers) may detect and identify each other. The process by which this mutual detection and identification between peers takes place may be referred to as peer discovery. System 100 may support peer discovery by providing that peers desiring to establish peer-to-peer communication periodically transmit short messages and listen to the transmissions of others.

Transmissions for peer discovery may periodically occur during specified times referred to as peer discovery intervals, the timing of which may be predetermined by a protocol and known to wireless terminals 102. Peers may be synchronized to a common clock reference. For example, wireless terminals 102 may decode a small amount of broadcast information from locally positioned base station 104. Synchronization may allow for peers in a given geographic location to recognize a start and a finish of each discovery interval.

The local area peer-to-peer network and the wide area network may share a common wireless spectrum to effectuate communication; thus, bandwidth may be shared for transferring data via the disparate types of networks. For example, the peer-to-peer network and the wide area network may both communicate over the licensed spectrum. However, the peer-to-peer communication need not utilize the wide area network infrastructure.

Now turning to FIG. 2, illustrated is a system 200 that synchronizes communication between wireless terminals in a peer-to-peer network. System 200 includes a wireless terminal 202 that communicates directly with substantially any number of disparate wireless terminals (e.g., disparate wireless terminal 1 204, . . . , disparate wireless terminal X 206, where X may foe any integer). Although the following provides further detail with regards to wireless terminal 202, it is to be appreciated that such illustrations may similarly apply to disparate wireless terminals 204-206.

Wireless terminal 202 may further include a synchronizer 208 that conforms timing between wireless terminal 202 and disparate wireless terminals 204-206. Synchronizer 208 may obtain its timing from a common clock reference. Similar synchronizers (not shown) of disparate wireless terminals 204-206 may obtain their respective timing from the same common clock reference. Further, synchronizer 208 may utilize a predetermined protocol to evaluate the common clock reference to identify a type of function to be effectuated at the time associated with the common clock reference (e.g., current time). Thus, for example, synchronizer 208 and similar synchronizers (not shown) of disparate wireless terminals 204-206 may determine that a time period identified from the common clock reference may be employed for one of peer discovery, paging, or traffic. The time period identified will be substantially the same or similar for synchronizer 208 and similar synchronizers (not shown) of disparate wireless terminals 204-206, even though wireless terminals 202-206 have not directly communicate with each other.

The common clock reference utilized by synchronizer 208 may be broadcast information from a base station (not shown) in a vicinity of wireless terminal 202 and disparate wireless terminals 204-206. Another common clock reference may include GPS satellite signals, For example, the broadcast information may be a Beacon, a PN (pseudo random) sequence signal, a pilot signal or other broadcast signal. Further, the broadcast signal may be periodically received from the base station. Moreover, timing information may be determined from the broadcast signal by synchronizer 208. By way of illustration, wireless terminal 202 and disparate wireless terminals 204-206 may receive and synchronize to the same broadcast signal, and therefore, have a common understanding of time. The common notion of time may be utilized to partition a timeline into distinct periods for each type of function (e.g., peer discovery, paging, traffic) according to a predetermined pattern defined by the air interface protocol.

Additionally, wireless terminal 202 may include a peer discovery communicator 210 that effectuates peer discovery during a peer discovery interval as determined by synchronizer 208. Peer discovery communicator 210 may further comprise a signal broadcaster 212 and a peer detector 214. Signal broadcaster 212 may transmit a message, in a first portion of the peer discovery interval, to disparate wireless terminals 204-206 that enables disparate wireless terminals 204-206 to detect and identify wireless, terminal 202. Further, in a second portion of the peer discovery interval, peer detector 214 may receive message(s) sent from disparate wireless terminal(s) 204-206; peer detector 214 may analyze the received message(s) to detect and identify disparate wireless terminal(s) 204-206 to which the message(s) correspond. In some embodiments, the first and the second portions of the peer discovery interval may not overlap in time. Further, a transmit/receive switch guard time may be reserved between the first and the second portions of the peer discovery interval.

By way of example, wireless terminal 202 may enter into a peer-to-peer network that includes disparate wireless terminal 1 204 and disparate wireless terminal X 206. Upon entering the network, synchronizer 208 may determine timing associated with peer-to-peer communications (e.g., based upon a received common clock reference). Further, at a time partitioned for peer discovery, signal broadcaster 212 may broadcast a signal to disparate wireless terminals within range (e.g., disparate wireless terminals 204-206). The signal may be utilized by disparate wireless terminals 204-206 to detect that wireless terminal 202 has entered the network and/or determine an identity of wireless terminal 202. Moreover, peer detector 214 may obtain broadcast signals from disparate wireless terminals 204-206, Peer detector 214 may analyze the obtained signals to detect disparate wireless terminals 204-206 and/or identify disparate wireless terminals 204-206.

Peer discovery effectuated by peer discovery communicator 210 may be passive. Further, peer discovery may be symmetric; thus, wireless terminal 202 may detect and identify disparate wireless terminal 1 204 and disparate wireless terminal 1 204 may detect and identify wireless terminal 202. However, it is contemplated that a first wireless terminal may detect and identify a second wireless terminal, but the second wireless terminal may fail to detect and identify the first wireless terminal. Moreover, the defined time interval utilized for peer discovery may be much shorter than the time between peer discovery intervals. Additionally, upon detection and identification, further communication (e.g., paging, traffic) between wireless terminal 202 and disparate wireless terminal(s) 204-206 may, but need not, be effectuated.

Referring to FIG. 3, illustrated is an example timing diagram 300 utilized by synchronized peers communicating within a peer-to-peer environment. Timing diagram 300 may be partitioned with intervals for peer discovery as well as intervals for differing functions such as paging and communicating traffic. As noted above, peers may be synchronized with one another based upon a common clock reference; thus, the peers may have a common notion of timing diagram 300. Peer discovery intervals 302 are illustrated. Each peer discovery interval 302 may have a duration of T₀. Peer discovery intervals 302 may be dedicated for detecting and identifying peers. Further, the time between peer discovery intervals 302 may be T₁. Any number of paging and/or traffic intervals may be included during T₁ between adjacent peer discovery intervals 302. The terminal may transition to a sleep mode (e.g., for power saving) during T₁ interval, for example, when the terminal does not find any peer in the peer discovery interval or does not find any peer of interest.

The amount of time allocated for peer discovery may be a small fraction of the overall time. For instance, the time (T₁) between peer discovery intervals may be at least 5 times larger than the time (T₀) allotted for each peer discovery interval 302. Pursuant to another example, the ratio of T₁ to T₀ may be 10, 50, 100, 200, 300, and so forth, According to a further example, peer discovery intervals 302 may have a duration, T₀, on the order of 2 ms (e.g., around 10 ms, 50 ms, . . . ). By way of further illustration, T₁, the time between peer discovery intervals, may be on the order of a few seconds or 1 minute. Allocating a small portion of overall time for peer discovery provides efficient utilization of power, since peers not involved in communicating pages and/or traffic may sleep during the time, T₁, in between each peer discovery interval 302.

With reference to FIG. 4, illustrated is an example timing diagram 400 of a peer discovery interval. The peer discovery interval may include a number of possible transmission times during which a wireless terminal can broadcast a signal. For instance, the peer discovery interval may include N symbols (e.g., OFDM symbols), where N may be any integer. Further, each symbol may last 10 μs and N may be 50, 100, 200, etc.; however, the subject claims are not so limited. Each peer within a peer-to-peer network may transmit utilizing one or more of the symbols; the peer may listen to the remainder of the symbols to detect and/or identify other peers within range. In accordance with an example, a peer may transmit on a first symbol at a first time and a second symbol at a second time, where the first time and the second time may or may not be contiguous.

According to an example, the peer discovery interval may include 200 symbols. In one or more embodiments, the 200 symbols may be used for transmitting broadcast signals by the terminals. In other embodiments, every other symbol may be utilized for transmission (e.g., 100 symbols may be employed for transmission). Before the peer discovery interval, each wireless terminal that, wishes to engage in peer-to-peer communication may select one or more transmission symbols (e.g., out of the total of 100 transmission symbols pursuant to the above example). During the selected symbol time(s), the wireless terminal transmits a message to disparate wireless terminal(s) (e.g., peer(s)). The message may include one tone in one of the selected transmission symbols. Further, during at least a fraction of the remaining symbol times in the peer discovery interval, the wireless terminal listens and decodes the transmissions of the disparate wireless terminal(s). Since peer-to-peer communication may employ a half-duplex mode, where a wireless terminal either transmits or receives data at a particular time, the wireless terminal may transmit for 10% of the transmission times and receive for the remaining 90% of the time. By way of another example, the wireless terminal may transmit 30% of the time and receive 70% of the time. In accordance with an illustration, the wireless terminal may determine the transmission time(s) and/or the waveform (e.g., the frequency tone transmitted in a selected transmission symbol) to transmit based upon an identifier and/or a notion of time (e.g., derived from a received Beacon). The notion of time is in essence a time-varying variable. All the wireless terminals may get the same notion of time. For example, the wireless terminals may obtain a time-varying variable from the broadcast (e.g., beacon) signal from the base station. The time-varying variable can be some variable transmitted in the broadcast signal. For example, the variable can be some time counter or system time, which varies over time. In this document, the notion of time is referred to as time counter. It is desired that the time counter varies from one peer discovery interval to another. By way of further example, the wireless terminal may utilize a pseudo-random number generator, whose seed can be an identifier of the wireless terminal and a current counter value supplied by a broadcast signal from a base station, to select transmission time(s) and/or the waveform. As the time counter varies, the selected transmission symbol time(s) and/or waveform may also vary from one peer discovery interval to another.

Referring now to FIG. 5, illustrated is a system 500 that effectuates synchronized communications over a peer-to-peer network. System 500 includes wireless terminal 202 that may communicate via a peer-to-peer network with disparate wireless terminal(s) (e.g., peer(s)). Wireless terminal 202 may include synchronizer 208 that coordinates performance of various functions (e.g., peer discovery, paging, traffic). Synchronizer 208 may obtain and analyze a common clock reference to determine a meaningful notion of time. Additionally, the disparate wireless terminal(s) may obtain and analyze the common clock reference to yield the same notion of time; hence, peers within a local area may synchronize with the same common clock reference (e.g., from the same base station). Therefore, peers get the same timing (timing synchronized) without directly communicating with each other. For example, the common clock reference may be a Beacon signal transmitted by a base station within range of wireless terminal 202 and the peers. Further, wireless terminal 202 may comprise peer discovery communicator 210, which further includes signal broadcaster 212 and peer detector 214.

Peer discovery communicator 210 may also include a signal generator 502 that yields a message to be sent by signal broadcaster 212, According to an example, signal generator 502 may determine transmission time(s) within a peer discovery interval and/or waveform(s) to be transmitted. Signal generator 502 may yield transmission time(s) and/or waveform(s) of the message as a function of an identifier (ID) (e.g., corresponding to wireless terminal 202) and a time (e.g., determined from common clock reference). In accordance with an example, the message yielded by signal generator 502 may be a Beacon signal, which may provide power efficiency; thus, signal generator 502 may effectuate transmitting a particular tone on a selected OFDM symbol. It is contemplated that more than one Beacon signal may be transmitted. Further, due to privacy issues, safeguards may be put into place to mitigate undesired distribution of the ID of wireless terminal 202.

Pursuant to another example, signal generator 502 may provide signal broadcaster 212 with an ID associated with wireless terminal 202 that may be broadcast to peer(s). Peer(s) obtaining the ID may detect and identify wireless terminal 202 by utilizing the received ID. For example, the ID of wireless terminal 202 may be an output of an M-bit hash function whose input is the plain-text name of wireless terminal 202 and a current counter value supplied by a base station broadcast signal (e.g., common clock reference, Beacon, . . . ). The counter value, for instance, may be constant during a current peer discovery interval and may be decodable by ail peers. Further, the hash function may be specified a priori by a protocol and known to the peers.

By way of an example, peer detector 214 may maintain a list of plain-text names, of buddy peers associated with wireless terminal 202. Further, upon decoding a particular ID, peer detector 214 may hash its plain-text buddy names using the current, counter value. If at least one of the output IDs matches the decoded ID, peer detector 214 may conclude that the corresponding buddy peer is present If no match is found or there are multiple matches, peer detector 214 may be unable to conclude as to the presence of any buddy peers. Moreover, each peer may vary the number of bits, previously denoted by M, of the output of the ID generating hash function in order to ensure that it is eventually discovered. A peer maintains a list of disparate wireless terminals that are detected to be present in the current time. The list may include all disparate wireless terminals or may include those In the predefined buddy list of wireless terminal 202 or the user who is using wireless terminal 202. As the time goes by, the list evolves, because some disparate wireless terminals may disappear (e.g., because the corresponding users move away), or because other disparate wireless terminals may appear (e.g., because the corresponding users move close). The peer may add the new disparate wireless terminals to the list or delete disappearing disparate wireless terminals from the list. In an embodiment, the peer passively maintains the list. In this case, a first peer may detect the presence of a second peer and keep the second peer in its list without informing the second peer. As a result, the second peer may not know that the first peer has already kept the second peer in the list. By symmetry, depending on wireless channel and interference condition, the second peer may also detect the presence of the first peer and keep the first peer in its list without informing the first peer. In another embodiment, after the first peer detects the presence of the second peer, the first peer proactively sends a signal to inform the second peer so that the second peer now knows that the first peer has already kept the second peer in the list, even though the first peer has no data traffic to communicate with the second peer yet. The first peer may selectively decide whether it sends a signal. For example, the first peer may send a signal only to another peer that is in the predefined buddy list.

Wireless terminal 202 may also include a pager 504 and a traffic communicator 506. Based upon the synchronized notion of time yielded by synchronizer 208, pager 504 and traffic communicator 506 may transmit and/or receive signals via the peer-to-peer network during respective, allocated times for such functions. Upon detecting and identifying a peer, pager 504 enables wireless terminal 202 to initiate communication with the peer. Further, during an allotted traffic interval, wireless terminal 202 and the peer may transmit and/or receive traffic by employing traffic communicator 506.

Wireless terminal 202 may additionally include a state transitioner 508. To provide power savings, state transitioner 508 may enable wireless terminal 202 to enter a sleep state during time intervals associated with functions (e.g., paging, traffic) other than peer discovery when wireless terminal 202 is not involved with such functions. Further, state transitioner 508 switches wireless terminal 202 to an on state (e.g., from a sleep state) during peer discovery intervals to enable wireless terminal 202 to discover peer(s) and/or be discovered by peer(s).

Moreover, wireless terminal 202 may include memory 510 and a processor 512. Memory 510 may retain an identifier associated with wireless terminal 202. Further, memory 510 may include a list a buddy peers mat may be referenced by peer detector 214. Additionally, memory 510 may retain instructions related to synchronizing time intervals for differing functions with disparate wireless terminals, establishing a common period of time for peer discovery in a local area (e.g., based upon information obtained from a base station), identifying location(s) within a peer discovery interval for broadcasting wireless terminal related signals, generating signals for transmission to disparate wireless terminals, detecting and/or identifying disparate wireless terminals within range, and so forth. Moreover, processor 512 may execute instructions, described herein.

In accordance with an example, the peer-to-peer network may operate in the same frequency band as the cellular network (e.g., wide area network). In this case, peers may obey a transmit power cap in order to mitigate excessive interference caused for uplink cellular mobiles. For example, an open-loop power control may be utilized whereby wireless terminal 202 may estimate its path gain to the base station by measuring a received power of a signal from the base station. Thus, each peer may select its transmit power under the constraint that the received power at the base station is less than a certain threshold.

Since typical communication distances are on the order of meters for tens of meters) for peer-to-peer communication, the symbol duration can be made significantly shorter as compared to cellular communication because the delay spread may be shorter. Consequently, time division duplex (TDD) peer-to-peer communication can be accomplished with less delay than in a cellular system since the switching time between transmitting and listening may be reduced. For example, the symbol duration may be 10 μs, with a cyclic prefix covering roughly 1 μs of delay spread.

Referring to FIG. 6, illustrated is an example time-frequency grid 600 associated with transmission during a peer discovery interval. The x-axis represents time and may include N symbols (e.g., where N may be any integer), and the y-axis represents frequency and may include M tones (e.g., where M may be any integer). According to an example, a wireless terminal may select a particular symbol (e.g., transmission time) for transmission (e.g., based upon an identifier of the wireless terminal or the user who is using the wireless terminal and/or time counter). Further, a particular tone corresponding to the selected symbol may be determined (e.g., based upon the identifier and/or time). Thus, the x and y coordinates (e.g., (x₁, y₁) within grid 600, as illustrated by the shading, may provide information (e.g., when evaluated by a peer receiving such signal). By transmitting a single symbol, the alphabet employed by the wireless terminal may be log₂ (M·N). According to a further example, more than one symbol may be utilized by the wireless; terminal for transmission: during the peer discovery interval. Pursuant to this example, the tones (e.g., Beacons) may be transmitted at different times. By way of illustration, if two Beacons are transmitted with coordinates (x₁, y₁) and (x₂, y₂), x₁ differs from x₂ to mitigate transmitting the two Beacons concurrently.

Referring to FIGS. 7-9, methodologies relating to performing peer discovery within a peer-to-peer network are illustrated. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with one or more embodiments.

Turning to FIG. 7, illustrated is a methodology 700 that facilitates operating a wireless terminal in a peer-to-peer network. At 702, a signal may be received from a signal source (e.g., base station, an access node, a GPS satellite, . . . ). The signal may be broadcast by a base station in a vicinity of the peer-to-peer network; thus, a wireless terminal performing synchronization as well as other wireless terminals (e.g., that may similarly effectuate synchronization) in the peer-to-peer network may obtain a common signal from the same base station. Further, the signal may be a common clock reference. Pursuant to an example, the signal may be a Beacon, a PN (pseudo random) sequence signal, a pilot signal, etc. Moreover, the signal may be periodically received.

At 704, time positions of a sequence of peer discovery intervals may be determined based upon the signal. Thus, a first wireless terminal may determine a first sequence of peer discovery intervals. Peer discovery intervals may be synchronized between wireless terminals in a peer-to-peer network. For example, a second wireless terminal may receive the signal from the signal source and determine a second sequence of peer discovery intervals based upon the signal, wherein the second sequence may substantially overlap with the first sequence in time. Timing information may be derived from the received signal. Moreover, since the same signal may be employed by differing wireless terminals, the wireless terminals may have a common notion of time. Further, the common notion of time may be utilized to partition a timeline into distinct periods for differing types of functions (e.g., peer discovery, paging, traffic). According to an example, the amount of time mat separates two successive peer discovery intervals in the sequence may be at least 5 times larger than a duration of time of either of the successive peer discovery intervals. Pursuant to a further example, the amount of time that separates two successive peer discovery intervals in the sequence of peer discovery intervals may be at least 100 times larger than the duration of time of either of the two successive peer discovery intervals. Additionally, meaningfully defined paging intervals and/or traffic intervals may be identified based upon the received signal. In accordance with an example, a plurality of paging intervals and a plurality of traffic intervals may be positioned between adjacent peer discovery intervals. Moreover, a wireless terminal may transition to an on state from a power saving state (e.g., sleep state) before a peer discovery interval-starts (e.g., if the wireless terminal lacks involvement in active traffic prior to the peer discovery interval). Also, the wireless terminal may switch to a power saving state (e.g., sleep state) from an on state after a peer discovery interval ends (e.g., if the wireless terminal lacks involvement in active traffic subsequent to the peer discovery interval).

Now referring to FIG. 8, illustrated is a methodology 800 that facilitates transmitting a message that enables peers to detect and identify a wireless device in a peer-to-peer network. At 802, a signal may be obtained from a signal source (e.g., base station, access node, GPS satellite, . . . ). For example, a time may be derived from the signal. Moreover, for instance, the base station may be associated with a wide area network, and a common spectrum (e.g., licensed spectrum) may be shared between the wide area network and the peer-to-peer network. At 804, time positions of a sequence of peer discovery intervals may be identified based upon the obtained signal. For example, timing of the sequence of peer discovery intervals may be specified by a predetermined protocol commonly known within the peer-to-peer network (e.g., known by differing wireless terminals included in the peer-to-peer network). Further, paging and/or traffic intervals may be identified based upon the obtained signal. The partitioned intervals of the peer-to-peer network, for instance, may enable short range, high data rate communication between peers.

At 806, at least one symbol within each of the peer discovery intervals of the sequence may be selected based on an identifier and a time counter variable derived from the signal. It is to be appreciated that one or more symbols, which represent a first fraction of each peer discovery interval, may be selected. Moreover, the identifier may relate to a wireless terminal and/or a user currently utilizing the wireless terminal It is contemplated that a position of the selected symbol(s) within a peer discovery interval may vary from one peer discovery interval to another. Additionally, a value of the time counter variable may vary from one peer discovery interval to another. Further, selection of symbol(s) may be effectuated prior to each peer discovery period and may be specified by a protocol known across the peer-to-peer network. According to an example, each peer discovery period may include N symbols (e.g., OFDM symbols), where N is any integer. Further, each of the N symbols may correspond to a unique transmission time (e.g., each symbol may last 10 μs). Moreover, a half-duplex mode may be employed such that either transmission or reception occurs at each time, but not both transmission and reception. According to an example, transmission time may be 10% of a duration of each peer discovery interval or less (e.g., and 90% of the duration may be utilized for listening). Pursuant to another example, the transmission time may account for 30% of the duration of each peer discovery interval, while 70% may be employed for receiving. At 808, a single tone (e.g., message) may be broadcast on each of the selected symbols. For example, the tone may be used to send a Beacon signal (e.g., to enhance efficiency). The frequency location of the tone may be determined based on the identifier and/or the time counter variable. Additionally, the frequency location of the tone may vary from one peer discovery interval to another in the sequence of peer discovery intervals. Also, a transmission power of the tone may be at least 10 times higher than a transmission power of any other tone in the same symbol. Further, if more than one Beacon is broadcast (e.g., from one wireless terminal), different symbols may correspond to each of the Beacons.

With reference to FIG. 9, illustrated is a methodology 900 that facilitates detecting and identifying peers in a peer-to-peer network. At 902, a signal may be obtained from a signal source. At 904, time positions of a sequence of peer discovery intervals may be identified based upon the obtained signal. For example, the sequence may be synchronized in time, with a disparate sequence of peer discovery intervals determined by a disparate wireless terminal. At 906, listening may occur during, a fraction of each of the peer discovery intervals. For example, listening may be effectuated for at least 70% of each peer discovery interval, while the remainder may be employed for transmitting, According to another example, 90% or more of a peer discovery interval may be utilized by a wireless terminal for listening. Moreover, one or more symbols selected for transmitting during each of the peer discovery intervals may be excluded from the respective fraction for listening associated with each peer discovery interval. At 908, a broadcast message (e.g., signal) from a peer may be detected while listening during the fraction of a current peer discovery interval. For example, the broadcast message may be obtained at a time that differs from time(s) utilized for transmission by a receiving peer; thus, the fraction of the current peer discovery interval during which detection occurs may be distinct from a differing fraction of the current peer discovery interval employed for transmission. By way of further illustration, a tone and a symbol may be determined from the detected broadcast message. At 910, an identifier (e.g., of the peer and/or a user employing the peer) may be decoded from the broadcast message. By way of illustration, the identifier may be decoded based upon a time counter variable derived from the signal obtained from the signal source.

The first fraction of each peer discovery interval mentioned in FIG. 8, which is used for transmitting a broadcast message, and the second fraction of each peer discovery interval mentioned in FIG. 9, which is used for detecting broadcast messages from other terminals, do not overlap in time. In an embodiment, the second traction is no less than the first fraction. In some cases, the second fraction may be 2, 4, 8, 16, 50, etc. times larger than the first fraction.

According to an example, upon detecting the broadcast message of the peer and decoding the corresponding identifier for the peer, such identifier may be added to a list of identifiers that represents detected terminals. Pursuant to another example, a buddy list of buddy identifiers may be retained in memory and the decoded identifier may be compared with the buddy identifiers in the buddy list; further, the decoded identifier may be marked as one of the buddy identifiers if the comparison result indicates that the detected identifier is substantially similar to one of the buddy identifiers in the buddy list. Continuing this example, a signal may be transmitted to the peer associated with the decoded identifier that, informs the peer that it has been identified.

It will be appreciated that, in accordance with one or more aspects described herein, inferences can be made regarding discovering and identifying peers in a peer-to-peer environment. As used herein, the term to “infer” or “inference” refers generally to the process of reasoning about or inferring states of the system, environment, and/or user from a set of observations as captured via events and/or data. Inference can be employed to identify a specific context or action, or can generate a probability distribution over states, for example. The inference can be probabilistic—that is, the computation of a probability distribution over states of interest based on a consideration of data and events. Inference can also refer to techniques employed for composing higher-level events from a set of events and/or data. Such inference results in the construction of new events or actions from a set of observed events and/or stored event data, whether or not the events are correlated in close temporal proximity, and whether the events and data come from one or several event and data sources.

According to an example, one or more methods presented above can include making inferences pertaining to synchronizing a peer discovery interval for utilization in connection with communicating via the peer-to-peer network. In accordance wife another example, an inference may be made related to estimating a common notion of time from a broadcast signal in the peer-to-peer network. It will be appreciated that the foregoing examples are illustrative in nature and are not intended to limit the number of inferences that can be made or the manner in which such inferences are made in conjunction with the various embodiments and/of methods described herein.

FIG. 10 depicts an example communication system 1000 implemented in accordance with various aspects including multiple cells: cell I 1002, cell M 1004. Note that neighboring cells 1002, 1004 overlap slightly, as indicated by cell boundary region 1068, thereby creating potential for signal interference between signals transmitted by base stations in neighboring cells. Each cell 1002, 1004 of system 1000 includes three sectors. Cells which have not be subdivided into multiple sectors (N=1), cells with two sectors (N=2) and cells with more than 3 sectors (N>3) are also possible in accordance with various aspects. Cell 1002 includes a first sector, sector I 1010, a second sector, sector II 1012, and a third sector, sector III 1014. Each sector 1010, 1012, 1014 has two sector boundary regions; each boundary region is shared between two adjacent sectors.

Sector boundary regions provide potential for signal interference between signals transmitted by base stations in neighboring sectors. Line 1016 represents a sector boundary region between sector I 1010 and sector II 1012; line 1018 represents a sector boundary region between sector II 1012 and sector III 1014; line 1020 represents a sector boundary region between sector III 1014 and sector I 1010. Similarly, cell M 1004 includes a first sector, sector I 1022, a second sector, sector II 1024, and a third sector, sector III 1026. Line 1028 represents a sector boundary region between sector I 1022 and sector II 1024; line 1030 represents a sector boundary region between sector II 1024 and sector III 1026; line 1032 represents a boundary region between sector III 1026 and sector I 1022. Cell I 1002 includes a base station (BS), base station I 1006, and a plurality of end nodes (ENs) (e.g., wireless terminals) in each sector 1010, 1012, 1014. Sector I 1010 includes EN(1) 1036 and EN(X) 1038 coupled to BS 1006 via wireless links 1040, 1042, respectively; sector II 1012 includes EN(1′) 1044 and EN(X′) 1046 coupled to BS 1006 via wireless links 1048, 1050, respectively; sector III 1014 includes EN(1″) 1052 and EN(X″) 1054 coupled to BS 1006 via wireless links 1056, 1058, respectively. Similarly, cell M 1004 includes base station M 1008, and a plurality of end nodes (ENs) in each sector 1022, 1024, 1026. Sector I 1022 includes EN(1) 1036′ and EN(X) 1038′ coupled to BS M 1008 via wireless links 1040′, 1042′, respectively; sector II 1024 includes EN(1′) 1044′ and EN(X′) 1046′ coupled to BS M 1008 via wireless links 1048′. 1050′, respectively; sector 3 1026 includes EN(1″) 1052′ and EN(X″) 1054′ coupled to BS 1008 via wireless links 1056′, 1058′, respectively.

System 1000 also includes a network node 1060 which is coupled to BS I 1006 and BS M 1008 via network links 1062, 1064, respectively. Network node 1060 is also coupled to other network nodes, e.g., other base stations, AAA server nodes, intermediate nodes, routers, etc. and the Internet via network link 1066. Network links 1062, 1064, 1066 may be, e.g., fiber optic cables. Each end node, e.g., EN(1) 1036 may be a wireless terminal including a transmitter as well as a receiver. The wireless terminals, e.g., EN(1) 1036 may move through system 1000 and may communicate via wireless links with the base station in the cell in which the EN is currently located. The wireless terminals, (WTs), e.g., EN(1) 1036, may communicate with peer nodes, e.g., other WTs in system 1000 or outside system 1000 via a base station, e.g., BS 1006, and/or network node 1060. WTs, e.g., EN(1) 1036 may be mobile communications devices such as cell phones, personal data assistants with wireless modems, etc. Respective base stations perform tone subset allocation using a different method for the strip-symbol periods, from the method employed for allocating tones and determining tone hopping in the rest symbol periods, e.g., non strip-symbol periods. The wireless terminals use the tone subset allocation method along with information received from the base station, e.g., base station slope ID, sector ID information, to determine tones that they can employ to receive data and information at specific strip-symbol periods. The tone subset allocation sequence is constructed, in accordance with various aspects to spread inter-sector and inter-cell interference across respective tones.

Local area peer-to-peer communication may also be supported by communication system 1000. For example, a common spectrum may be utilized for both local-area peer-to-peer communication as well as communication via the wide area network (e.g., cellular infrastructure network). Wireless terminals may communicate with other peers via a local area peer-to-peer network such as peer-to-peer networks 1070, 1072, and 1074. Although three peer-to-peer networks 1070-1074 are depicted, it is to be appreciated that any number, size, shape, etc. of peer-to-peer networks may be supported. For instance, each peer-to-peer network 1070-1074 may support transfer of signals directly between wireless terminals. Further, each peer-to-peer network 1070-1074 may include wireless terminals within a similar geographic area (e.g., within range of one another). For example, EN( ) 1036 may communicate with EN(X) 1038 by way of the local area peer-to-peer network 1070. However, it is to be appreciated that wireless terminals need not be associated with the same sector and/or cell to be included in a common peer-to-peer network. Further, peer-to-peer networks may overlap (e.g., EN(X′) 1046 may leverage peer-to-peer networks 1072 and 1074). Additionally, a wireless terminal may not be supported by a peer-to-peer network. Wireless terminals may employ the wide area network and/or the peer-to-peer network where such networks overlap (e.g., concurrently or serially). Moreover, wireless terminals may seamlessly switch or Concurrently leverage such networks. Accordingly, wireless terminals whether transmitting and/or receiving may selectively employ one or more of the networks to optimize communications.

FIG. 11 illustrates an example base station 1100 in accordance with various aspects. Base station 1100 implements tone subset allocation sequences, with different tone subset allocation sequences generated for respective different sector types of the cell. Base station 1100 may be used as any one of base stations 1006, 1008 of the system 1000 of FIG. 10. The base station 1100 includes a receiver 1102, a transmitter 1104, a processor 1106, e.g., CPU, an input/output interface 1108 and memory 1110 coupled together by a bus 1109 over which various elements 1102, 1104, 1106, 1108, and 1110 may interchange data and information.

Sectorized antenna 1103 coupled to receiver 1102 is used for receiving data and other signals, e.g., channel reports, from wireless terminals transmissions from each sector within the base station's cell. Sectorized antenna 1105 coupled to transmitter 1104 is used for transmitting data and other signals, e.g., control signals, pilot signal, beacon signals, eta to wireless terminals 1200 (see FIG. 12) within each sector of the base station's cell. In various aspects, base station 1100 may employ multiple receivers 1102 and multiple transmitters 1104, e.g., an Individual receiver 1102 for each sector and an individual transmitter 1104 for each sector. Processor 1106, may be, e.g., a general purpose central processing unit (CPU). Processor 1106 controls operation of base station 1100 under direction of one or more routines 1118 stored in memory 1110 and implements the methods. I/O interface 1108 provides a connection to other network nodes, coupling the BS 1100 to other base stations, access routers, AAA server nodes, etc., other networks, and the Internet. Memory 1110 includes routines 1118 and data/information 1120.

Data/Information 1120 includes data 1136, tone subset allocation sequence information 1138 including downlink strip-symbol time information 1140 and downlink tone information 1142, and wireless terminal (WT) data/info 1144 including a plurality of sets of WT information: WT 1 info 1146 and WT N info 1160. Each set of WT info, e.g., WT 1 info 1146 includes data 1148, terminal ID 1150, sector ID 1152, uplink channel information 1154, downlink channel information 1156, and mode information 1158.

Routines 1118 include communications routines 1122 and base station control routines 1124. Base station control routines 1124 includes a scheduler module 1126 and signaling routines 1128 including a tone subset allocation routine 1130 for strip-symbol periods, other downlink tone allocation hopping routine 1132 for the rest of symbol periods, e.g., non strip-symbol periods, and a beacon routine 1134.

Data 1136 includes data to be transmitted that will be sent to encoder 1114 of transmitter 1104 for encoding prior to transmission to WTs, and received data from WTs that has been processed through decoder 1112 of receiver 1102 following reception. Downlink strip-symbol time information 1140 includes the frame synchronization structure information, such as the superslot, beaconslot, and ultraslot structure information and information specifying whether a given symbol period is a strip-symbol period, and if so, the index of the strip-symbol period and whether the strip-symbol is a resetting point to truncate the tone subset allocation sequence used by the base station. Downlink tone information 1142 includes information including a carrier frequency assigned to the base station 1100, the number and frequency of tones, and the set of tone subsets to be allocated to the strip-symbol periods, and other cell and sector specific values such as slope, slope index and sector type.

Data 1148 may include data that WT1 1200 has received from a peer node, data that WT 1 1200 desires to be transmitted to a peer node, and downlink channel quality report feedback information. Terminal ID 1150 is a base station 1100 assigned ID that identifies WT 1 1200. Sector ID 1152 includes information identifying the sector in which WT1 1200 is operating. Sector ID 1152 can be used, for example, to determine tire sector type. Uplink channel information 1154 includes information identifying channel segments that have been allocated by scheduler 1126 for WT1 1200 to use, e.g., uplink traffic channel segments for data, dedicated uplink control channels for requests, power control, timing control, etc. Each uplink channel assigned to WT1 1200 includes one or more logical tones, each logical tone following an uplink hopping sequence. Downlink channel information 1156 includes information identifying channel segments that have been allocated by scheduler 1126 to carry data and/or information to WT1 1200, e.g., downlink traffic channel segments for user data. Each downlink channel assigned to WT1 1200 includes one or more logical tones, each following a downlink hopping sequence. Mode information 1158 includes information identifying the state of operation of WT1 1200, e.g. sleep, hold, on.

Communications routines 1122 control the base station 1100 to perform various communications operations and implement various communications protocols. Base station control routines 1124 are used to control the base station 1100 to perform basic base station functional tasks, e.g., signal generation and reception, scheduling, and to implement, the steps of the method of some aspects including transmitting signals to wireless terminals using the tone subset allocation sequences during the strip-symbol periods.

Signaling routine 1128 controls the operation of receiver 1102 with its decoder 1112 and transmitter 1104 with its encoder 1114. The signaling routine 1128 is responsible for controlling the generation of transmitted data 1136 and control information. Tone subset allocation routine 1130 constructs the tone subset to be used in a strip-symbol period using the method of the aspect and using data/information 1120 including downlink strip-symbol time info 1140 and sector ID 1152, The downlink tone subset allocation sequences will be different for each sector type in a cell and different for adjacent cells. The WTs 1200 receive the signals in the strip-symbol periods in accordance with the downlink tone subset allocation sequences; the base station 1100 uses the same downlink tone subset allocation sequences in order to generate the transmitted signals. Other downlink tone allocation hopping routine 1132 constructs downlink tone hopping sequences, using information including downlink tone information 1142, and downlink channel information 1156, for the symbol periods other than the strip-symbol periods. The downlink data tone hopping sequences are synchronized across the sectors of a cell. Beacon routine 1134 controls the transmission of a beacon signal, e.g., a signal of relatively high power signal concentrated on one or a few tones, which may be used for synchronization purposes, e.g., to synchronize the frame timing structure of the downlink signal and therefore the tone subset allocation sequence with respect to an ultra-slot boundary.

FIG. 12 illustrates an example wireless terminal (e.g., end node, mobile device, . . . ) 1200 which can be used as any one of the wireless terminals (e.g., end nodes, mobile devices, . . . ), e.g., EN(1) 1036, of the system 1000 shown in FIG. 10. Wireless terminal 1200 implements the tone subset allocation sequences. Wireless terminal 1200 includes a receiver 1202 including a decoder 1212, a transmitter 1204 including an encoder 1214, a processor 1206, and memory 1208 which are coupled together by a bus 1210 over which the various elements 1202, 1204, 1206, 1208 can interchange data and information. An antenna 1203 used for receiving signals from a base station 1100 (and/or a disparate wireless terminal) is coupled to receiver 1202. An antenna 1205 used for transmitting signals, e.g., to base station 1100 (and/or a disparate wireless terminal) is coupled to transmitter 1204.

The processor 1206 (e.g., a CPU) controls operation of wireless terminal 1200 and implements methods by executing routines 1220 and using data/information 1222 in memory 1208.

Data/information 1222 includes user data 1234, user information 1236, tone subset allocation sequence information 1250, and a buddy peer list 1256. User data 1234 may include data, intended for a peer node, which will be routed to encoder 1214 for encoding prior to transmission by transmitter 1204 to base station 1100, and data received from the base station 1100 which has been processed by the decoder 1212 in receiver 1202. User information 1236 includes uplink channel information 1238, downlink channel information 1240, terminal ID information 1242, base station ID information 1244, sector ID information 1246, and mode information 1248. Uplink channel information 1238 includes information identifying uplink channels segments that have been assigned by base station 1100 for wireless terminal 1200 to use when transmitting to the base station 1100. Uplink channels may include uplink traffic channels, dedicated uplink control channels, e.g., request channels, power control channels and timing control channels, Each uplink channel includes one or more logic tones, each logical tone following an uplink tone hopping sequence. The uplink hopping sequences are different between each sector type of a cell and between adjacent cells. Downlink channel information 1240 includes information identifying downlink channel segments that have been assigned by base station 1100 to WT 1200 for use when BS 1100 is transmitting data/information to WT 1200. Downlink channels may include downlink traffic channels and assignment channels, each downlink channel including one or more logical tone, each logical tone following a downlink hopping sequence, which is synchronized between each sector of the cell.

User Info 1236 also includes terminal ID information 1242, which is a base station 1100 assigned identification, base station ID information 1244 which identifies the specific base station 1100 that WT has established communications with, and sector ID info 1246 which identifies the specific sector of the cell where WT 1200 is presently located. Base station ID 1244 provides a cell slope value and sector ID info 1246 provides a sector index type; the cell slope value and sector index type may be used to derive tone hopping sequences. Mode information 1248 also included in user info 1236 identifies whether the WT 1200 is in sleep mode, hold mode, or on mode.

Tone subset allocation sequence information 1250 includes downlink strip-symbol time information 1252 and downlink tone information 1254. Downlink strip-symbol time information 1252 include the frame synchronization structure information, such as the superslot, beaconslot, and ultraslot structure information and information specifying whether a given symbol period is a strip-symbol period, and if so, the index of the strip-symbol period and whether the strip-symbol is a resetting point to truncate the tone subset allocation sequence used by the base station. Downlink tone info 1254 includes information including a carrier frequency assigned to the base station 1100, the number and frequency of tones, and the set of tone subsets to be allocated to the strip-symbol periods, and other cell and sector specific values such as slope, slope index and sector type.

Routines 1220 include communications routines 1224, wireless terminal control routines 1226, synchronization routines 1228, signal generation/broadcast routines 1230, and detection routines 1232. Communications routines 1224 control the various communications protocols used by WT 1200, For example, communications routines 1224 may enable communicating via a wide area network (e.g., with base station 1100) and/or a local area peer-to-peer network (e.g., directly with disparate wireless terminal(s)). By way of further example, communications routines 1224 may enable receiving a broadcast signal (e.g., from base station 1100). Wireless terminal control routines 1226 control basic wireless terminal 1200 functionality including the control of the receiver 1202 and transmitter 1204. Synchronization routines 1228 control synchronizing wireless terminal 1200 to a received signal (e.g., from base station 1100). Peers within a peer-to-peer network may also be synchronized to the signal. For example, the received signal may be a Beacon, a PN (pseudo random) sequence signal, a pilot signal, etc. Further, the signal may be periodically obtained and a protocol (e.g., associated with synchronization routines 1228) also known to peers may be utilized to identify intervals corresponding to distinct functions (e.g., peer discovery, paging, traffic). Signal generation/broadcast routines 1230 control creating a message for transmission during an identified peer discovery interval. A symbol and/or tone associated with the message may be selected based upon a protocol (e.g., associated with signal generation/broadcast routines 1230). Moreover, signal generation/broadcast routines 1230 may control sending the message to peers within the peer-to-peer network. Detection routines 1232 control detection and identification of peers based upon messages received during an identified peer discovery interval. Further, detection routines 1232 may identify peers based at least in part upon information retained in buddy peer list 1256.

With reference to FIG. 13, illustrated is a system 1300 that enables synchronizing a time period for discovery of peers in a peer-to-peer network. For example, system 1300 may reside at least partially within a wireless terminal. It is to be appreciated that system 1300 is represented as including functional blocks, which may be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System 1300 includes a logical grouping 1302 of electrical components that can act in conjunction. For instance, logical grouping 1302 may include an electrical component for receiving a signal from a signal source 1304. Pursuant to an illustration, the signal source may be a base station, an access point, a GPS satellite, and so forth. For example, the signal may be broadcast to the peer-to-peer network. Moreover, the peers may obtain a common notion of time based upon the received signal. Further, logical grouping 1302 may comprise an electrical component for locating time positions of a sequence of peer discovery intervals based upon the signal 1306. A length of time for each of the peer discovery intervals, for instance, may be at least 5 times smaller than a length of time between two neighboring peer discovery intervals. Further, a subset of potential transmission times from the peer discovery interval may be selected for transmission (e.g., based upon a time derived from the received signal and/or an identifier), for example. Moreover, the transmitted message may be utilized for detection and/or identification. Additionally, system 1300 may include a memory 1308 that retains instructions for executing functions associated with electrical components 1304 and 1306. While shown as being external to memory 1308, it is to be understood that one or more of electrical components 1304 and 1306 may exist within memory 1308.

It is to be understood that the embodiments described herein may be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the processing units may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof.

When the embodiments are implemented in software, firmware, middleware or microcode, program code or code segments, they may be stored in a machine-readable medium, such as a storage component. A code segment may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted using any suitable means including memory sharing, message passing, token passing, network, transmission, etc.

For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art.

What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim. 

What is claimed is:
 1. A method of operating a first wireless terminal in a peer-to-peer network, comprising: receiving a first signal from a signal source wherein the signal source is at least one of a base station, an access node, or a GPS satellite; determining time positions of a first sequence of peer discovery intervals based upon the received first signal; and wherein an amount of time that separates two successive peer discovery intervals in the first sequence of peer discovery intervals is at least 100 times larger than a duration of time of either of the two successive peer discovery intervals.
 2. The method of claim 1, further comprising: transitioning to an on state from a power saving state before a peer discovery interval starts; and switching to the power saving state from the on state after the peer discovery interval ends.
 3. A method of operating a first wireless terminal in a peer-to-peer network, comprising: receiving a first signal from a signal source wherein the signal source is at least one of a base station, an access node, or a GPS satellite; determining time positions of a first sequence of peer discovery intervals based upon the received first signal; selecting at least one symbol within each of the peer discovery intervals of the first sequence based on a first identifier of either the first wireless terminal or a user currently using the first wireless terminal and a time counter variable derived from the first signal; broadcasting a second signal on each of the selected symbols; and wherein an amount of time that separates two successive peer discovery intervals in the first sequence of peer discovery intervals is at least 5 times larger than a duration of time of either of the two successive peer discovery intervals.
 4. A method of operating a first wireless terminal in a peer-to-peer network, comprising: receiving a first signal from a signal source wherein the signal source is at least one of a base station, an access node, or a GPS satellite; determining time positions of a first sequence of peer discovery intervals based upon the received first signal; selecting at least one symbol within each of the peer discovery intervals of the first sequence based on a first identifier of either the first wireless terminal or a user currently using the first wireless terminal and a time counter variable derived from the first signal; broadcasting a second signal on each of the selected symbols; listening during a fraction of each of the peer discovery intervals; detecting a third broadcast signal from a peer while listening during the fraction of a current peer discovery interval; and decoding a second identifier from the third broadcast signal if it is determined that the third broadcast signal is present.
 5. The method of claim 4, wherein the second identifier is decoded based on the time counter variable.
 6. The method of claim 4, wherein the at least one selected symbol is excluded from the fraction of each of the peer discovery intervals for listening.
 7. The method of claim 4, wherein the at least one symbol selected for broadcasting the second signal within each of the peer discovery intervals corresponds to less than 30% of a duration of each of the peer discovery intervals and wherein the fraction for listening corresponds to at least 70% of the duration of each of the peer discovery intervals.
 8. The method of claim 4, further comprising: adding the decoded second identifier to a first list of identifiers wherein the first list of identifiers represents detected terminals.
 9. The method of claim 4, further comprising: storing a second list of buddy identifiers; comparing the decoded second identifier with buddy identifiers in the second list of buddy identifiers; and marking the decoded second identifier as a particular one of the buddy identifiers if the comparison result indicates that the decoded second identifier is substantially similar to the particular one of the buddy identifiers in the second list of buddy identifiers.
 10. The method of claim 9, further comprising: transmitting a signal to the peer associated with the decoded second identifier; and informing the peer that it has been identified.
 11. A method of operating a first wireless terminal in a peer-to-peer network, comprising: receiving a first signal from a signal source wherein the signal source is at least one of a base station, an access node, or a GPS satellite; determining time positions of a first sequence of peer discovery intervals based upon the received first signal; selecting at least one symbol within each of the peer discovery intervals of the first sequence based on a first identifier of either the first wireless terminal or a user currently using the first wireless terminal and a time counter variable derived from the first signal; broadcasting a second signal on each of the selected symbols; and wherein the value of the time counter variable varies from one peer discovery interval to another in the first sequence of peer discovery intervals and a position of the at least one selected symbol within each of the peer discovery intervals varies from one peer discovery interval to another.
 12. The method of claim 11, wherein the second signal includes a tone.
 13. The method of claim 12, wherein a frequency location of the tone is selected based on the first identifier and the time counter variable and the frequency location of the tone varies from one peer discovery interval to another in the first sequence of peer discovery intervals.
 14. The method of claim 12, wherein a transmission power of the tone is at least 10 times higher than a transmission power of any other tone in the same symbol.
 15. A wireless communications apparatus, comprising: a memory that retains instructions related to obtaining a first signal from a signal source and identifying time positions of a first sequence of peer discovery intervals based upon the obtained first signal; a processor, coupled to the memory, configured to execute the instructions retained in the memory; and wherein the memory further retains instructions for separating two successive peer discovery intervals in the first sequence by an amount of time at least 100 times a length of time of either of the two successive peer discovery intervals.
 16. The wireless communications apparatus of claim 15, wherein the memory further retains instructions for transitioning to and from an on state before a start of a peer discovery interval and after an end of the peer discovery interval, respectively.
 17. A wireless communications apparatus, comprising: a memory that retains instructions related to: obtaining a first signal from a signal source; identifying time positions of a first sequence of peer discovery intervals based upon the obtained first signal; separating two successive peer discovery intervals in the first sequence by an amount of time at least 5 times a length of time of either of the two successive peer discovery intervals; and selecting at least one symbol within each of the peer discovery intervals of the first sequence based on a first identifier and a time counter variable derived from the first signal, and broadcasting a second signal on each of the selected symbols; and a processor, coupled to the memory, configured to execute the instructions retained in the memory.
 18. The wireless communications apparatus of claim 17, wherein the memory further retains instructions for varying the time counter variable between peer discovery intervals in the first sequence and varying a position of the at least one selected symbol within each of the peer discovery intervals from one peer discovery interval to another.
 19. A wireless communications apparatus, comprising: a memory that retains instructions related to obtaining a first signal from a signal source and identifying time positions of a first sequence of peer discovery intervals based upon the obtained first signal; a processor, coupled to the memory, configured to execute the instructions retained in the memory; wherein the memory further retains instructions for selecting at least one symbol within each of the peer discovery intervals of the first sequence based on a first identifier and a time counter variable derived from the first signal, and broadcasting a second signal on each of the selected symbols; and wherein the memory further retains instructions for listening during a fraction of each of the peer discovery intervals, detecting a third broadcast signal from a peer during the fraction of a current peer discovery interval employed for listening, and decoding a second identifier from the third broadcast signal when detected.
 20. The wireless communications apparatus of claim 19, wherein the memory further retains instructions for decoding the second identifier based on the time counter variable.
 21. The wireless communications apparatus of claim 19, wherein the memory further retains instructions for excluding the at least one selected symbol from the listening related fraction of each of the peer discovery intervals.
 22. The wireless communications apparatus of claim 19, wherein the memory further retains instructions for broadcasting less than 30% of a duration of each of the peer discovery intervals and listening for the remainder of each duration.
 23. The wireless communications apparatus of claim 19, wherein the memory further retains instructions for adding the decoded second identifier to a first list of identifiers that represents detected terminals.
 24. The wireless communications apparatus of claim 19, wherein the memory further retains a second list of buddy identifiers and instructions for comparing the decoded second identifier with buddy identifiers in the second list and identifying the decoded second identifier as a particular one of the buddy identifiers when the decoded second identifier is substantially similar to the particular one of the buddy identifiers in the second list.
 25. A wireless communications apparatus, comprising: a memory that retains instructions related to obtaining a first signal from a signal source and identifying time positions of a first sequence of peer discovery intervals based upon the obtained first signal; a processor, coupled to the memory, configured to execute the instructions retained in the memory; wherein the memory further retains instructions for selecting at least one symbol within each of the peer discovery intervals of the first sequence based on a first identifier and a time counter variable derived from the first signal, and broadcasting a second signal on each of the selected symbols; wherein the memory further retains instructions for varying the time counter variable between peer discovery intervals in the first sequence and varying a position of the at least one selected symbol within each of the peer discovery intervals from one peer discovery interval to another; and wherein the memory further retains instructions for choosing a frequency location of a tone included in the second signal on a per peer discovery interval basis as a function of the first identifier and the time counter variable.
 26. A wireless communications apparatus that enables synchronizing a time period for discovery of peers in a peer-to-peer network, comprising: a memory device including a communication routine; means for receiving a first signal from a signal source; means for locating time positions of a first sequence of peer discovery intervals based upon the first signal; and means for separating successive peer discovery intervals in the first sequence by a time that is at least 100 times as long as a duration of each of the successive peer discovery intervals.
 27. The wireless communications apparatus of claim 26, further comprising means for switching to and from a power saving state after an end of or before a beginning of a peer discovery interval, respectively.
 28. A wireless communications apparatus that enables synchronizing a time period for discovery of peers in a peer-to-peer network, comprising: a memory device including a communication routine; means for receiving a first signal from a signal source; means for locating time positions of a first sequence of peer discovery intervals based upon the first signal; means for separating successive peer discovery intervals in the first sequence by a time that is at least 5 times as long as a duration of each of the successive peer discovery intervals; means for selecting at least one symbol within each of the peer discovery intervals of the first sequence based on a first identifier and a time counter variable derived from the first signal; and means for transmitting a broadcast of a second signal on each of the selected symbols.
 29. The wireless communications apparatus of claim 28, further comprising: means for listening during a fraction of each of the peer discovery intervals; means for detecting a third broadcast signal from a peer during the fraction of a present peer discovery interval employed for listening; and means for decoding a second identifier from the third broadcast signal when detected based on the time counter variable.
 30. The wireless communications apparatus of claim 29, further comprising means for enforcing a maximum percentage of a duration of each of the peer discovery intervals utilized for transmitting the broadcast on the selected symbols.
 31. The wireless communications apparatus of claim 28, further comprising: means for varying the time counter variable from one peer discovery interval to the next; means for varying a position of the at least one selected symbol within each of the peer discovery intervals from one peer discovery interval to another; and means for selecting a frequency location of a tone included in the second signal on a per peer discovery interval basis as a function of the first identifier and the varying time counter variable.
 32. In a wireless communication system, an apparatus comprising: a processor configured to: obtain a periodic signal from a base station; determine time positions of a sequence of peer discovery intervals based upon the obtained periodic signal, wherein the sequence of peer discovery intervals is synchronized between peers of a peer-to-peer network; select at least one symbol within each of the peer discovery intervals of the sequence based on a first identifier and a time counter variable derived from the first signal, and broadcast a second signal on each of the selected symbols; listen during a fraction of each of the peer discovery intervals; detect a third broadcast signal from a peer during the fraction of a current peer discovery interval employed for listening; and decode a second identifier from the third broadcast signal when the third broadcast signal is detected. 